Compositional analysis of water-soluble materials in corn stover
ABSTRACT Corn stover is one of the leading feedstock candidates for commodity-scale biomass-to-ethanol processing. The composition of water-soluble materials in corn stover has been determined with greater than 90% mass closure in four of five representative samples. The mass percentage of water-soluble materials in tested stover samples varied from 14 to 27% on a dry weight basis. Over 30 previously unknown constituents of aqueous extracts were identified and quantified using a variety of chromatographic techniques. Monomeric sugars (primarily glucose and fructose) were found to be the predominant water-soluble components of corn stover, accounting for 30-46% of the dry weight of extractives (4-12% of the dry weight of feedstocks). Additional constituents contributing to the mass balance for extractives included various alditols (3-7%), aliphatic acids (7-21%), inorganic ions (10-18%), oligomeric sugars (4-12%), and a distribution of oligomers tentatively identified as being derived from phenolic glycosides (10-18%).
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ABSTRACT: Solid-state anaerobic digestion (SS-AD) and composting of yard trimmings with effluent from liquid AD were compared under thermophilic condition. Total solids (TS) contents of 22%, 25%, and 30% were studied for SS-AD, and 35%, 45%, and 55% for composting. Feedstock/effluent (F/E) ratios of 2, 3, 4, 5, and 6 were tested. In composting, the greatest carbon loss was obtained at 35% TS, which was 2-3 times of that at 55% TS and was up to 50% higher than that in SS-AD. In SS-AD, over half of the degraded carbon was converted to methane with the greatest methane yield of 121L/kgVSfeedstock. Methane production from SS-AD was low at F/E ratios of 2 and 3, likely due to the inhibitory effect of high concentrations of ammonia nitrogen (up to 5.6g/kg). The N-P-K values were similar for SS-AD digestate and compost with different dominant nitrogen forms.Bioresource Technology 07/2014; 169C:439-446. DOI:10.1016/j.biortech.2014.07.007 · 5.04 Impact Factor
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ABSTRACT: Corn straw was chemically and anatomically characterised. Hydrothermal processing (autohydrolysis) was used for the selective solubilisation of hemicelluloses. The raw material was treated under non-isothermal conditions (150-240 degrees C) and the effects on the composition of both liquid and solid phases were evaluated. The yields and composition of the solid fraction and soluble products are presented and interpreted using the severity factor (log R-0). The operational conditions for the maximum yield of xylo-oligosaccharides (XOS) of 53% of initial xylan, were established for log R-0 of 3.75. Under these conditions 72% of xylan was hydrolysed while cellulose and lignin were not substantially affected although an increase in the enzymatic digestibility of cellulose was attained. For the severest condition (log R-0 =4.51) the solids contained 61.7% glucan and 31.0% lignin. The XOS rich liquors and the glucan and lignin enrichment of the solid phase make corn straw a suitable raw material in a biorefinery framework and the hydrothermal treatment a favourable first step in the processing.Industrial Crops and Products 08/2013; Indust Crops Prod(50):145. DOI:10.1016/j.indcrop.2013.06.037 · 3.21 Impact Factor
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ABSTRACT: Hydrothermal carbonization (HTC) is a pretreatment process for making a homogenized, carbon rich, and energy-dense solid fuel, called biochar, from lignocellulosic biomass. Corn stover, miscanthus, switch grass, and rice hulls were treated with hot compressed water at 200, 230, and 260 °C for 5 min. Mass yield is as low as 41% of the raw biomass, and decreases with increasing HTC temperature. Higher heating values (HHV) increase up to 55% with HTC pretreatment temperature. Up to 90% of calcium, magnesium, sulfur, phosphorus, and potassium were removed with HTC treatment possibly due to hemicellulose removal. At a HTC temperature of 260 °C, some structural Si was removed. All heavy metals were reduced by HTC treatment. The slagging and fouling indices are reduced with HTC treatment relative to that of untreated biomass. Chlorine content, a concern only for raw and HTC 200 switch grass, was reduced to a low slagging range at 230 °C, and 260 °C. Alkali index was medium for raw biomass but decreased by HTC.Biomass and Bioenergy 02/2013; 49:86-94. DOI:10.1016/j.biombioe.2012.12.004 · 3.41 Impact Factor